Heat sealable PVC blends

Abstract

Blends of styrene-butadiene rubber and PVC latices in a dry weight ratio of 45:10 to 55:70 are useful to form heat sealable films. The mixture does not contain plasticizers and thus reduces environmental concerns during processing. The resulting film have good clarity and flexibility and may be used to seal textiles, non-wovens and boards.

What is claimed is: 
     
       1. A heterogeneous, heat sealable composition comprising: A) from 10 to 70 parts by dry weight of a latex of a vinyl polymer comprising: i) 100 to 75 weight percent of vinyl or vinylidene chloride; and   ii) up to 25 weight percent of a C 2-8  alkyl acrylate;     B) from 20 to 70 parts by dry weight of a carboxylated vinyl aromatic monomer-conjugated diolefin polymer comprising: i) 40 to 60 weight percent of a C 8-12  of said vinyl aromatic monomer which is unsubstituted or substituted by a C 1-4  alkyl radical chlorine atom or mixtures thereof;   ii) from 39.5 to 59.5 weight percent of a C 4-6  straight or branched chain of said conjugated diolefin which is unsubstituted or substituted by a chlorine atom or a mixture thereof;   iii) from 0.5 to 10 weight percent of a C 3-6  ethylenically unsaturated carboxylic acid; and   iv) from 0 to 5 weight percent of one or more monomers selected from the group consisting of:   a) C 1-8  alkyl and hydroxyalkyl esters of C 3-6  ethylenically unsaturated carboxylic acid;   b) amides of C 3-6  ethylenically unsaturated carboxylic acids, which amides are unsubstituted or substituted at the nitrogen atom by up to two radicals selected from the group consisting of C 1-4  alkyl and hydroxyalkyl radicals; and   c) C 3-6  ethylenically unsaturated aldehydes.     
     
     
       2. A composition process according to claim 1 wherein said vinyl polymer is present in an amount from 30 to 40 parts by weight. 
     
     
       3. A composition according to claim 2, wherein said vinyl polymer is present in an amount of 35 parts by weight. 
     
     
       4. A composition according to claim 3 wherein said carboxylated polymer is present in an amount from 50 to 65 parts by weight. 
     
     
       5. A composition according to claim 4 wherein said vinyl polymer comprises: A) 100 to 80 weight percent of vinyl chloride; and   B) up to 20 weight percent of one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate and ethylhexyl acrylate.   
     
     
       6. A composition according to claim 5 wherein said carboxylated as a latex comprises: A) from 45 to 55 weight, percent of one or more monomers said vinyl aromatic selected from the group consisting of styrene, alpha methyl styrene or a mixture thereof;   B) from 54.5 to 44.5 weight percent of one or more monomers said diolefin selected from the group consisting of butadiene, isoprene and chloroprene;   C) from 0.5 to 5 weight percent of one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, and itaconic acid; and   D) optionally up to 5 weight percent of one or more monomers selected from the group consisting of ethyl acrylate, propyl acrylate, butyl acrylate, ethylhexyl acrylate, and N-methylol acrylamide.   
     
     
       7. A composition according to claim 6 wherein said vinyl polymer comprises 75 to 80 weight percent of vinyl chloride and 20 to 25 weight percent of ethyl acrylate. 
     
     
       8. A composition according to claim 7 wherein said carboxylated polymer comprises: A) 45 to 55 weight percent of styrene;   B) from 54.5 to 44.5 weight percent of butadiene; and   C) from 0.5 to 5 weight percent of acrylic acid.